Liquid crystal displays are commonly used as displays for compact electronic apparatuses, because they not only provide good quality images with little power but are also very thin.
Referring to FIG. 6, a typical liquid crystal display 6 includes an upper polarizing film 60, a liquid crystal panel 61, a lower polarizing film 62, an upper BEF 63, a lower BEF 64, a diffusing film 65, a light guide plate (LGP) 66, and a reflective film 67, arranged in that order from top to bottom. Each of the upper BEF 63 and the lower BEF 64 includes a plurality of linear prism structures 69 formed at a respective main body (not labeled) thereof. The prism structures 69 of the upper BEF 63 are perpendicular to the prism structures 69 of the lower BEF 64. The upper BEF 63 and the lower BEF 64 can improve a brightness of the liquid crystal display 6.
However, the prism structures 69 are exposed at outsides of the respective main bodies of the upper BEF 63 and the lower BEF 64. In a process of assembling the liquid crystal display 6, the prism structures 69 are liable to be scraped. When this occurs, an optical performance of the liquid crystal display 6 may be degraded. Further, the upper BEF 63 and the lower BEF 64 are separate from each other, and a step of aligning the upper BEF 63 and the lower BEF 64 is generally needed. The step is typically performed by manual labor, and adds to the cost of manufacturing the liquid crystal display 6.
What is needed, therefore, is a BEF that can overcome the above-described deficiencies. What are also needed are a backlight module and a liquid crystal display employing the BEF.